This book describes in detail two kinds of models that simulate the dispersion of radionuclides in the sea. Biases have a strong impact on the predictable skill and the structures of the model predicted patterns in the tropical Atlantic Ocean. These biases and the related effects are presented as well as the atmospheric teleconnections between the tropical Atlantic and the African continent. Special focus is given to recent developments in the nitrogen cycle in the open ocean and the new challenges that have arisen from these advancements. This book also provides a review of the history, geography, and climate of the Atlantic and Indian Oceans, as well as the role they play in natural disasters. A review of the tsunami hazard along the coastal area of the Gulf of Bengal is explored and the seismicity of the Indian Ocean area. The Indian Ocean Dipole (IOD) and its affects, such as monsoon strength over the Indian subcontinent, climatic extremes and socio-economic hardship throughout the tropical Indian Ocean region are presented. This book considers a selection of statistical time series models to analyze and predict the IOD. Finally, using a data-assimilative model of the North Indian assimilating altimetry, the seasonal and inter-annual variability of the meridional heat fluxes in the Indian Ocean are explored.